The present disclosure relates to editing digital audio data.
Digital audio data can be provided by a multitude of audio sources. Examples include audio signals from an FM radio receiver, a compact disc drive playing an audio CD, a microphone, or audio circuitry of a personal computer (e.g., during playback of an audio file).
The audio data in an audio signal can be edited. For example, the audio signal may include noise or other unwanted audio data. Removing unwanted audio data improves audio quality (e.g., the removal of noise components provides a clearer audio signal).
Alternatively, a user may apply different processing operations to portions of the audio signal to generate particular audio effects.
GSM (Global System for Mobile communications) is a communications network for mobile phones using a time division multiple access method. GSM devices emit signals at predetermined intervals. Thus, GSM data transmissions can interact with other devices to generate noise that can then be captured by particular audio capture devices. For example, a telephone conference can include one or more speakerphones having high-gain audio amplifiers and associated cables (e.g., telephone line from speakerphone to jack). These can cooperate to act as an antenna for the GSM signals emitted from mobile phones of the participants.
In particular, the GSM emissions can induce signals in nearby devices. The induced signals, for example in the speakerphone, can result in audible noise broadcast by the speakerphone. Similarly, placing a GSM mobile phone near typical computer speakers will produce a similar noise from the computer speakers. This noise can then be captured by audio capture devices (e.g., a microphone recording the telephone conference).
The GSM signals induce current spikes at a particular frequency depending on a GSM rate (e.g., 217 Hz which corresponds to a noise spike substantially every 4.5 ms). The spikes, or GSM pulses, may occur at integer multiples of the frequency interval (e.g., 4.5(x) ms where “x” is an integer). GSM pulses are typically short in duration, e.g., substantially three milliseconds. Additionally, the noise caused by the GSM signals can cover a broad range of frequencies. Consequently, the GSM pulse can mask the underlying audio data, for example, the voices participating in the conference call.